Potential Operation of Battery Systems to Provide Automatic Frequency Reserve Restoration (aFRR) Service

As a consequence of the enormous growth being experienced by renewable energy systems (RES), conventional technologies such as coal or gas, which unlike RES are dispatchable, are reducing their participation in energy markets, increasing the instability of the electric energy systems. Therefore, there is a need for RES or other converter-based technologies to replace the traditional ancillary service providers. In this sense, battery energy storage systems (BESS) are considered the best candidates. This paper defines a model to simulate the Spanish Automatic Generation Control (AGC). This simulator is used to provide inputs to the operation of a BESS that participates in the secondary frequency regulation market and in the continuous intraday energy market. Subsequently, the paper introduces an economic feasibility study to determine the best BESS size to operate simultaneously in both markets. The results obtained show that BESS with energy capacities of 2 h are the best option (from both a technical and an economic point of view) to be part of a regulation zone.